This application relates generally to hydraulic devices of the type in which a series of pumping elements are carried by slots in a rotor and are spring urged toward engagement with a circumscribing cam ring. It relates particularly to a hydraulic device of the type in which the configuration of the rotor and/or the pumping elements serves to positively restrict undesirable spring movements of the type which might damage the springs or make the device unduly noisy.
In hydraulic devices of the type in which the pumping elements are formed by slippers which can move radially and rock angularly with respect to the rotor it is known that a spring helps to assure positive engagement of the slipper and the cam ring at low rotational speeds. Examples of such slipper-type hydraulic devices can be found in disclosures such as U.S. Pat. Nos. 2,641,195; 3,403,630; 3,645,647 and 3,797,977. Examples of other types of hydraulic devices in which a pumping element is spring biased toward engagement with a cam ring can be found in disclosures such as U.S. Pat. Nos. 3,223,044; 3,716,033 and 3,765,379.
In hydraulic devices of the slipper-type, two basic design techniques have been used to provide for resisting undesirable spring movement. One technique is to provide either a rotor slot or its associated slipper, or both, with a hole for receiving an end portion of the spring (which is usually a helical spring). When the rotor and pumping elements are molded of powdered metal, this technique requires that the holes be drilled into the rotor and/or pumping element.
Another technique for providing for resisting spring movement has been to provide the rotor or pumping element with a protrusion which extends into a portion of the helical spring.